Send all fields when transmitting an autosave.

[adamsilverstein]

Description

merges the post object with toSend before sending the autosave, ensuring that unedited fields are sent with their current values.

Fixes #7078

How has this been tested?

Create a post and publish it.
Change the content of the post and wait 10 seconds for the autosave to fire.
Check the autosave REST request - note that the title is present in the request. Check the database and note the autosave title is present in the database.

Changes

I found that altering the original object sets up an infinite save loop, to avoid this I create a new object to send to autosaves and leave toSend untouched.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.

[aduth]

Unlike title and excerpt, toSend will always have an assigned value for content, and thus will always override. This line will never take effect.

[aduth]

Also wondering: Since isEditedPostAutosaveable uses property values from state.autosave to consider a field as having been changed, should we be using those here as well as the original value to fall back to? Maybe with a getCurrentAutosave selector?

toSend = {
	...getCurrentAutosave(),
	...toSend,
	parent: post.id
};

[aduth]

Minor: If we use let instead of const to declare toSend, with spread syntax we could simplify this a bit:

toSend = {
	title: post.title,
	excerpt: post.excerpt,
	...toSend,
	parent: post.id
};

[aduth]

And if we want to take it a step further with Lodash's _.pick:

toSend = {
	...pick( post, [ 'title', 'excerpt' ] ),
	...toSend,
	parent: post.id
};

[aduth]

@adamsilverstein I just pushed d10a64e which accounts for all of my feedback. The request body accounts for both the fields from the current post, but preferring values from state.autosave. I'm a bit unclear about what value we're expecting state.autosave to hold over time: For example, if I have an autosave, but then proceed to save/publish the post, should the value revert back to null (reflecting the fact that there is no autosave?).

Otherwise there may be some edge cases where e.g. post is autosaved (state.autosave assigned), then published (state.autosave currently not assigned), then edits made: Values from state.autosave would incorrectly take precedent over the last saved post values.

I don't know that that needs to be addressed as part of this pull request specifically.

[youknowriad]

LGTM 👍